Health Library

What Is Conjunctivitis?

Conjunctivitis is an irritation or infection of the membrane that covers the white of the eye and the inside of the eyelid (conjunctiva). It can affect one or both eyes. The membrane swells and the blood vessels dilate (enlarge), making the eye red. That's why conjunctivitis is sometimes called red eye or pink eye.

What Are the Symptoms?

If you have one or more of these symptoms, see an eye doctor:

Redness in and around the eye

Eyes that are puffy and sore

Itching, burning, or stinging eyes

Watery eyes or discharge from the eye

Eyelids that are crusty or stuck together when you wake up in the morning

Prompt treatment helps prevent damage to your eyes.

How Is It Diagnosed?

Conjunctivitis usually isn't serious. But some more serious eye diseases have similar symptoms, so it's important for an eye doctor to diagnose you. Your eye doctor will ask about your symptoms, any medications you take, and any illnesses or medical conditions you may have. The doctor will also check your eyes with a hand-held light and a special microscope called a slit lamp.